Research conducted at the University of Arizona found COPPER can reduce microbial populations on surfaces. Through oxidation, where copper reacts with oxygen, a toxic residue is formed that can kill some susceptible strains of bacteria. The study looked at Salmonella, both susceptible and resistant strains. They found that bacteria, even those resistant to copper, could not survive long on copper surfaces.
Read full article here: "Study: Copper Kills Salmonella, Other Microbes" by James Andrews, Food Safety News, July 19, 2012